package com.study.结构型模式.外观模式;

public class Screen {

    private Screen(){}

    private static final class Instance{
        public static final Screen instance = new Screen();
    }

    public static Screen getInstance(){
        return Instance.instance;
    }

    public void up(){
        System.out.println("screen up");
    }

    public void down(){
        System.out.println("screen down");
    }
}
